Kansas City and Seattle have not only won three of the past four Super Bowls, they came into week seven with this season's best offence and best defence respectively, in terms of total yards.
Sunday's primetime match also marked the return of Kenneth Walker, the Most Valuable Player in last season's Super Bowl, to former team Seattle after joining the Chiefs in the off-season.
The running back has made a stunning start with Kansas City, leading the NFL in rushing yards per game (133) after six weeks, but Seattle's defence was determined to show why they became known as ['the Dark Side' during last season's championship run.](/sport/american-football/articles/c4gq5ze8eqyo)
They stifled Patrick Mahomes and the Chiefs, restricting Walker to 36 yards from 14 carries as KC tied for their fewest points in a game with Mahomes as their starting quarterback.
Seattle quarterback Sam Darnold also continued to lean on Jaxon Smith-Njigba, with last season's offensive player of the year claiming 150 receiving yards and a touchdown, while new running back Emanuel Wilson finished with 100 rushing yards and a score.
The Seahawks ran out 20-3 winners to improve their record to 4-3, while the Chiefs are now 5-1.